/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    Randomize.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.instance;

import java.util.Enumeration;
import java.util.Random;
import java.util.Vector;

import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Randomizable;
import weka.core.Utils;
import weka.core.WeightedAttributesHandler;
import weka.core.WeightedInstancesHandler;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 * <!-- globalinfo-start --> Randomly shuffles the order of instances passed
 * through it. The random number generator is reset with the seed value whenever
 * a new set of instances is passed in.
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -S &lt;num&gt;
 *  Specify the random number seed (default 42)
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Len Trigg (trigg@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class Randomize extends Filter implements UnsupervisedFilter, OptionHandler, Randomizable, WeightedInstancesHandler, WeightedAttributesHandler {

    /** for serialization */
    static final long serialVersionUID = 8854479785121877582L;

    /** The random number seed */
    protected int m_Seed = 42;

    /** The current random number generator */
    protected Random m_Random;

    /**
     * Returns a string describing this classifier
     * 
     * @return a description of the classifier suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String globalInfo() {
        return "Randomly shuffles the order of instances passed through it. " + "The random number generator is reset with the seed value whenever " + "a new set of instances is passed in.";
    }

    /**
     * Returns an enumeration describing the available options.
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> newVector = new Vector<Option>(1);

        newVector.addElement(new Option("\tSpecify the random number seed (default 42)", "S", 1, "-S <num>"));

        return newVector.elements();
    }

    /**
     * Parses a given list of options.
     * <p/>
     * 
     * <!-- options-start --> Valid options are:
     * <p/>
     * 
     * <pre>
     * -S &lt;num&gt;
     *  Specify the random number seed (default 42)
     * </pre>
     * 
     * <!-- options-end -->
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {

        String seedString = Utils.getOption('S', options);
        if (seedString.length() != 0) {
            setRandomSeed(Integer.parseInt(seedString));
        } else {
            setRandomSeed(42);
        }

        if (getInputFormat() != null) {
            setInputFormat(getInputFormat());
        }
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> options = new Vector<String>();

        options.add("-S");
        options.add("" + getRandomSeed());

        return options.toArray(new String[0]);
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String randomSeedTipText() {
        return "Seed for the random number generator.";
    }

    /**
     * Get the random number generator seed value.
     * 
     * @return random number generator seed value.
     */
    public int getRandomSeed() {

        return m_Seed;
    }

    /**
     * Set the random number generator seed value.
     * 
     * @param newRandomSeed value to use as the random number generator seed.
     */
    public void setRandomSeed(int newRandomSeed) {

        m_Seed = newRandomSeed;
    }

    public void setSeed(int seed) {
        setRandomSeed(seed);
    }

    public int getSeed() {
        return getRandomSeed();
    }

    /**
     * Returns the Capabilities of this filter.
     * 
     * @return the capabilities of this object
     * @see Capabilities
     */
    @Override
    public Capabilities getCapabilities() {
        Capabilities result = super.getCapabilities();
        result.disableAll();

        // attributes
        result.enableAllAttributes();
        result.enable(Capability.MISSING_VALUES);

        // class
        result.enableAllClasses();
        result.enable(Capability.MISSING_CLASS_VALUES);
        result.enable(Capability.NO_CLASS);

        return result;
    }

    /**
     * Sets the format of the input instances.
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true if the outputFormat may be collected immediately
     * @throws Exception if format cannot be processed
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        super.setInputFormat(instanceInfo);
        setOutputFormat(instanceInfo);
        m_Random = new Random(m_Seed);
        return true;
    }

    /**
     * Input an instance for filtering. Filter requires all training instances be
     * read before producing output.
     * 
     * @param instance the input instance
     * @return true if the filtered instance may now be collected with output().
     * @throws IllegalStateException if no input structure has been defined
     */
    @Override
    public boolean input(Instance instance) {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }
        if (m_NewBatch) {
            resetQueue();
            m_NewBatch = false;
        }
        if (isFirstBatchDone()) {
            push(instance);
            return true;
        } else {
            bufferInput(instance);
            return false;
        }
    }

    /**
     * Signify that this batch of input to the filter is finished. If the filter
     * requires all instances prior to filtering, output() may now be called to
     * retrieve the filtered instances. Any subsequent instances filtered should be
     * filtered based on setting obtained from the first batch (unless the
     * setInputFormat has been re-assigned or new options have been set). This
     * implementation randomizes all the instances received in the batch.
     * 
     * @return true if there are instances pending output
     * @throws IllegalStateException if no input format has been set.
     */
    @Override
    public boolean batchFinished() {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }

        if (!isFirstBatchDone()) {
            getInputFormat().randomize(m_Random);
        }
        for (int i = 0; i < getInputFormat().numInstances(); i++) {
            push(getInputFormat().instance(i), false); // No need to copy because of bufferInput()
        }
        flushInput();

        m_NewBatch = true;
        m_FirstBatchDone = true;
        return (numPendingOutput() != 0);
    }

    /**
     * Main method for testing this class.
     * 
     * @param argv should contain arguments to the filter: use -h for help
     */
    public static void main(String[] argv) {
        runFilter(new Randomize(), argv);
    }
}
